1. Field of the Invention
The present invention relates to a method of producing a surface acoustic wave device including a space-forming member for forming a space between a comb electrode and a reflector on a piezoelectric substrate, and to the surface acoustic wave device.
2. Description of the Related Art
In recent years, in a communications component or an electronic component, such as a portable telephone or a television receiver, a surface acoustic wave device (hereunder referred to as the “SAW device”) is used as, for example, a resonator or a band-pass filter.
The SAW device has a structure in which a surface acoustic wave element is covered and sealed with sealing resin. The surface acoustic wave element has, for example, a comb electrode and a reflector formed on a surface of a piezoelectric substrate. The surface (a function area) of the piezoelectric substrate where the comb electrode and the reflector are formed is provided with a space-forming member that forms a predetermined space between the comb electrode and the reflector. When the piezoelectric substrate is sealed with the sealing resin, the sealing resin adheres to, for example, the comb electrode that is already formed on the piezoelectric substrate. This causes a function of excitation of a surface acoustic wave provided by the comb electrode to be inhibited. The space-forming member is provided to restrict the inhibition of the excitation function.
In a related method of producing a SAW device, such a space-forming member is formed by combining a cover and four side frames. More specifically, the space-forming member is formed by forming four side frames (which define the space-forming member) as a result of performing patterning using photolithography techniques, after laminating a dry film resist to a surface of a surface acoustic wave element. The space-forming member is formed as a box member, in which these four side frames correspond to wall surfaces and the cover corresponds to a bottom surface, by adhering a film (serving as the cover) to the four side frames.
However, in the related method of forming a SAW device, two steps, the step of forming the four side frames and the step of forming the cover as a result of adhering the film to the four side frames, are required to form the space-forming member. Therefore, the manufacturing process is complicated.